A tool holder disclosed in, for example, PTL 1 is known as a tool holder in the related art. In the tool holder, a plate-like cutting insert is detachably disposed at the leading end portion of a shaft-shaped tool body, and the cutting insert includes a face, a flank, and a cutting edge that forms an intersection ridge between the face and the flank.
Further, an oil hole (coolant supply passage) in which a coolant (oil-based or water-soluble cutting fluid) flows is formed in the tool body, and a plate-like member including a recess is mounted on the leading end portion of the tool body. Furthermore, a coolant is ejected to the flank and the cutting edge from the oil hole through the recess of the plate-like member in a direction parallel to the flank of the cutting insert. This method of ejecting a coolant is referred to as a so-called jet coolant method, a JC method, and the like.
According to this structure, since it is difficult for a coolant to be affected by swarf in comparison with other structures that supply a coolant to the cutting edge from the face even though a coolant is supplied from outside or inside, the coolant easily reaches the cutting edge. For this reason, since the efficiency of the cooling of the cutting edge can be increased, the lengthening of the life of the insert and an increase in the efficiency of cutting can be expected.